Seagate Barracuda 7200.12 HDD PCB Components:

Hard Drive PCB Board Faults:

HDD PCB board is easily damaged, about 70% HDD failures caused by PCB. When HDD working, the 12V & 5V supply will be input to, Motor Controller Chip and Main Controller IC by TVS diodes and
capacitance. When the TVS diodes and capacitance subjected to a sustained overvoltage or the HDD is not used for a long time, will short the TVS diodes .The TVS diodes' short circuit will cause the HDD be burnt.

TVS Diode Burnt

Motor Controller Chip Burnt

Hard Drive PCB Main Components:

Hard Drive PCB Components

Hard Drive PCB Board Repair:

Most PCB failures are caused by Motor Controller Chip burnt, then the TVS diodes burnt and Main Controller IC burnt. In most cases, Motor Controller chip burnt by be seen by eyes. We can see a burnt hole or raised part on the Motor Controller IC. TVS diodes' short circuit can be test by a multimeter. Main Controller IC is difficult to be test. Burnt TVS diodes or Motor Controller IC can be repaired by using the same model chip or diodes. Of course, this operation is just be used by the technicians who has the Circuit repair knowledge. For common user, the best way is swap PCB.